The moment the Tank System was implemented into the game, many guilds began to purchase the Tanks. The implementation of the new system had sparked the guild to spend fortunes to secure as many Tanks as they could. Even though not all guilds were as rich as Zhang Yang's Lone Desert Smoke, they just had to buy at least one or two Tanks to stay in the game! After all, one Model 4.0 Tank would have much more HP than a player that has activated his or her Class S Inheritance Transformation! Of course, the guilds would need such a powerful asset on their sides.
Furthermore, the Tanks initially existed in the form of small models that could be held in one's hand. They were similar to the 'leash' of a pet. So, the guilds could just keep the number of Tanks they possessed hidden deep up their sleeves to create an element of surprise for their enemies. They would only reveal how many Tanks they had during very crucial moments in battle.